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June 4, 1963
3,092,674
W. W. BRAY, JR, ETAL
PROCESS FOR THE DEHYDROGENATION OF‘ OLEFINS
Filed June 11, 1959
FIGURE I
FIGURE 2
W|
Fel'
W- B'C'y J" INVENTORS
. Ponzek
BY
PATENT ATTORNEY
United States Patent 0 ”1C6
3,692,674
Patented June 4, 1953
1
2
3,092,674
pera-tures in said reactor at about ‘10000 to 1350° F. The
product e?iuent from the reactor must, of course be fur
ther processed by such means as quenching or cooling,
PROCESS FOR THE DEHYDROGENATIGN
OF OLEFINS
William W. Bray, lira, Scotch Piains, and Felix J. Ponzal-z,
New Brunswick, N.J., assignors to Esso Research and
EngineeringCompany, a corporation of Delaware
Filed June 11, 1959, Ser. No. 819,647
stripping, absorption, carbonyl removal and other puri?
cation steps. Additionally, if a combined stream is de
hydrogenated, complicated separation steps to obtain
desired pure products will usually be conducted. It is
therefore preferred to dehydrogenate only ‘a single com
ponent stream. This invention concerns only the inter
5 Claims. (Cl. 260—680)
relation of the reaction and regeneration steps per so so
This invention relates :to a new ‘and improved process
that these subsequent steps involving the puri?cation or
separation of the products obtained will not be discussed.
In general, the commercial system for this type of reaction
‘and apparatus for the dehydrogenation of C4-C6 ‘ole?ns
to diole?ns. More speci?cally, this invention relates to
a ?xed bed calcium nickel phosphate on ‘alumina catalyst
dehydrogenation process wherein the reactor catalyst bed
will comprise ‘a pair of reactors, one being employed as
the primary reactor while the other is subjected to re
is divided by a number of , plates disposed in parallel re
lation to the flow of vapors :thru the reactor. These plates
generation iand both being capable of being switched from
a reaction to regeneration operation and vice versa at in
provide a barrier against the horizontal spread of catalyst
tervals determined by the catalyst life between regenera
tions. Typical catalyst life between regenerations for the
utilized in the present invention deactivation or carbon 20 ‘dehydrogenation of CFCS :ole?ns or para?ins to diole?ns
is from 10 to 60 minutes. Such means for switching the
laydown proceeds from a particular point in the catalyst
deactivation vfrom one segment of the bed to other seg
ments of the bed.
Thus, with the particular catalysts
reactors may be automatic or manual :as desired.
bed by a growth or radiation outwardly through the bed.
Thus, carbon “mounds” :are formed in the catalyst bed
continual production of diole?ns is uninterrupted by the
which continually grow larger. Further, this invention
relates in ‘a preferred embodiment to blocking ‘0d a de
activated section of the bed during the dehydrogenation
cycle to thus halt laydown of carbon so that the particular
section of the catalyst bed can be completely restored by
a su?icient number of regeneration cycles. This must
be done before complete deactivation and pulverization
of the catalyst in the “mound” prevents any regeneration
of the catalyst. In another embodiment, this invention
relates to the utilization of a su?icient number of parallel
plates to divide [the bed into small narrow passageways
which will plug up when a carbon mound is formed
and thus prevent passage of vapors through the deac
tivated section of the bed unconverted.
Processes ‘for the dehydrogenation of butene to buta
dienes, isopentenes rand isopentanes to isoprene, and 2,3
dimethyl butene to 2,3-dimethy1 butadiene have been
known for many years.
The importance of the man
facture of these diole?ns has in the past few years been
increased by the mounting demand lfOl‘ rubber and rubber
substitutes and other copolymer products obtained from
these diole?ns. For example, butadiene is used in syn
thetic rubber, isoprene is ‘used in synthetic natural rub
ber ‘and 2,3-dimenhyl butadiene has been used as a sub
stitute for isoprene. One of the best known processes for
How
ever, it is preferable to have an arrangement whereby
25
switching operation.
In a preferred embodiment of this invention a vapor
.ized single component C4-C6 hydrocarbon feed is ad
mixed with superheated steam and contacted with a ?xed
bed of catalyst at elevated temperatures, the superheated
steam boosting the temperatures of the mixture to the
desired reaction temperature level. During the regen
eration period the vaporized hydrocarbon feed to the
catalyst bed is stopped and the catalyst bed purged of
all volatile hydrocarbons. After the purging, an oxygen
cont-aining regeneration gas, preferably air or 02 is ad
mitted in excess with superheated steam for timely and
adequate combustion of the carbonaceous deposits found
on the catalyst, and returning [the ‘catalyst to its proper
oxidation state. Finally, the regenerated catalyst is
purged of combustion products and brought back to re
action conditions.
The high temperatures and large proportions of steam
present
the reaction zone have caused dil?culties with
catalyst deactivation in the operation of the present type
process. Thus, the commercial units which are designed
‘to operate, ‘for ‘at least 6 months to pay ed the expensive
$1.85/lb. catalyst have been obtaining operations of only,
for example, 1% months before mounding (i.e. the growth
of a carbon mound in ‘a particular section of a catalyst
the preparation of these diole?ns involves the dehydro
genation of C4-C6 ole?ns or paraf?ns in the presence of 50 bed) requires shutdown of the unit. Ordinarily, this
catalyst must then be thrown away although attempts
certain catalysts which will be de?ned hereinafter and
have been made to obtain a regeneration or reactivation
in the presence of large proportions of steam, wherein
of the catalyst after mou-nding has occurred.
regeneration of the catalyst is carried out in the presence
It has now been found that much longer onstream
of steamv and air. A typical catalyst of the type amenable 55
periods can be obtained by longitudinally bathing the
to this reaction is calcium nickel phosphate. Other
reactor to prevent spreading of the carbon mound once
catalysts which may be used for this dehydrogenation to
diole?ns include alumina chromia catalyst or iron oxide
promoted by potassium carbonate. These catalysts are
it starts to other sections ‘of the bed.
It is further sug
gested according to this invention that by blanking off the
particular section of the bed where the mound starts to
without :a potassium promoter. An essential quality of 60 form with a cover, during the dehydrogenation part of
the cycle only, that the catalyst in said section can thus
the catalyst employed in the process of this invention is
be brought back to full use by destroying the mound by
its extremely high activity which, although not inhibited
burning it out in a number of regeneration cycles. Thus,
by large proportions of steam and high temperatures
in this latter embodiment a continuous operation is
which are necessary for obtaining the high selectivity to 65 obtained while at the same time the mound is removed
diole?ns in the primary reaction, is susceptible to the
at the expense of only a slight decrease in throughput.
“mounding” type of deactivation described above.
The arrangement of plates parallel to the how of vapors
Basically, the process per se comprises passing a com
which divide the reactor may be of the type shown in
bined stream .of superheated C4-C5 ole?ns and/o1- par
FIGURE 1 or it may be of the lattice or egg crate
a?ins or a single component such as butenes and large 70 dividing type shown in FIGURE 2 wherein a much larger
well known in the art and may be employed with or
quantities of steam into a reactor containing a solid
catalyst bed of .the desired type and maintaining the tem
number of separate catalyst sections is provided.
Turning now to FIGURE 1 the reaction chamber 1
3,092,674
3
4
V
.
of a dehydrogenattion reactor containing a catalyst bed
2 is shown. This catalyst bed is supported on a conven
tional grid not shown. The reaction vapors are passed
interpret the data obtained from the detection devices, it
has been possible to catch two incipient carbon mounds
and regenerate them successfully. On these occasions,
through the catalyst bed downwardly from above. The
plates 3 which are disposed substantially parallel to the
catalyst life has been kept in excess of 9 months. How
ever, there have been other occasions when the catalyst
?ow of vapors t-hru the reactor extend through the bed
mounds formed early in the runs, spread throughout the
bed, and were not able to be regenerated thus causing
large capital losses in catalyst investment.
,
blank o? a particular section. This cover may be hinged
In another operation three pairs of reactors using cal—
by hinges 5 and 6 and lifted by pulley 7 and cable 8 as
described in the ?gure or it may otherwise, be positioned 10 cium nickel phosphate catalyst were placed onstream in
July 1958. Of these units placed onstream in Iuly, two'
so that a section may be blanked off as desired. In a par
came down in December due to the presence of carbon
ticularly preferred embodiment a sample draw o? line
as shown.
If desired, a cover 4 may be provided to
may be located directly beneath each segment of the bed
mounds in the catalyst beds. Both had to be recharged
so that samples of the effluent gases may be passed to a
with new catalyst although eiforts were made to save
15 and regenerate the catalyst. The one unit which did not
carbon dioxide ‘analyzer during the regeneration cycle.
develop a carbon mound operated satisfactorily until
April 1959 when it too, developed a carbon mound.
Again the catalyst charge had to be discarded.
The following table represents general and speci?c con
cycle. Thus, carbon buildup is stopped and progressively
the regeneration gases passing through the mound during 20 ditions which may be employed in a process to produce
butadiene from normal butenes according to the present
the generation cycle burn out the carbon and restore
invention.
'
the section to full activity. The carbon dioxide and ana
lyzer indicates by a higher level of carbon dioxide in the
TABLE I
regeneration e?luent gases that a carbon mound is
Conditions ‘and Reactanls
being developed. Successful regeneration is indicated by 25
When the analyzer indicates that a carbon mound buildup
is occurring the particular deactivated section of the car
bon bed may be ‘blanked o? during the dehydrogenation
a reduction of carbon dioxide level in the ei?uent gases to
normal.
Alternatively, the reactor may be divided as shown in
FIGURE 2. Thus a number of parellel plates 11, 12, 13,
Catalyst:
The preferred catalyst comprises
14, 15 and 16 and 17, 18, 19, 20, 21 and 22 may be 30
Ni _____________________ __wt. pereent__
disposed in the reactor as shown preferably the number
Ca___
_______________ __ o____
of parallel plates is such that a particular section of the
PO4:_
__do.-._
01703
"6.0.".
bed de?ned by the plates has a horizontal area of 144
_
__d0__-to 4500 square inches. The advantage of this type of
General
Speci?c
4. 3-5.
5
27. 8-32. 0
30
' 49.0-60.5
57
1. 0-8. 0
6
1.0-3.0
2
Space velocity or nCr, v./v./hr.1 _________ ._
75-200
Space velocity of steam, v./v.lhr.l _______ __
1, 400-4, 000
2, 300
Reactor inlet temperature, ° F---
1, 000-1, 350
1, 175
_
50-100
15-30
30-60
70
20
40
Selectivity to butadiene, percent ........ __
out losing a large total part of the catalyst in the reactor.
Regeneration and Burner Conditions:
Space velocity of steam, v./v./hr.l _______ -As additional advantage of the use of such a ba?ie is 40
75-95
85
500-1, 000
675
parallel plate division is that the catalyst bed is divided 35
into a large number of small sections. Thus, mounding
may be allowed to proceed to completion in a particular
section, the spread thereof being closely contained, with
that the mound itself blocks oil the particular section and
thus prevents the passage of vapors through this section
unconverted. ,The catalyst dividers of the present inven
tion’ may be of stainless steel, or ordinary steel or of any
gas. impermeable material of sul?cient thickness’ and 45
strength to contain the catalyst in a substantially ?xed posi
tion in the reactor.
-
It is, of course, contemplated that the system described
Temp. drop across reactor, ° F-.Reactor outlet pressure, p.s.i.a_ _____-.
n-butylene conversion, percent per pass
Space velocity of air, v./v./hr.1__
Regenerator inlet temp., °
_
Temp. of e?luent gases, ° F_
Outlet pressure, p.s.i.a_ _ .-
Fuel gas to burner, lbs/hr ______ __
I 120
75-150
105
1, 000-1, 300
1, 175
1, 000-1, 300
1, 175
25-50
30
8-12
9
1 V./v./hr.—Vo1ume of gas at S.T.P./volume catalyst/hr. ‘
The same catalyst and all the above reaction and
regeneration conditions are also used in the process for
producing isoprene from isopentenes ore isopentenes ex
in this invention can be utilized in any other process
wherein deactivation spreads progressively from one sec 50 cept that reaction temperatures in the upper part of the
range given are preferred and a speci?c inlet temperature
tion of the catalyst bed to other sections of the catalyst
would thus be higher than that given, e.g., 1215° F. for
bed. Thus, for example, it will be of use in catalytic
isopentene and 1340° F. for the conversion of isopentane.
?xed bed reforming (for example, powerforming), hydro
Also, with respect to isopentane, conversions per pass
forming or similar ?xed bed processes.
This invention will be more clearly understood from 55 rather than 30-60% are only 10-20%. However, since
isopentane is comparatively inexpensive, the process is
a consideration of the following examples which present
still attractive.
'
data showing the deactivation occurring in commercial
The same catalyst and all the table I reaction and re
dehydrogenation units and also results obtained with at
generation conditions including ‘the speci?c conditions are
tempting to reactivate a catalyst after mounding has
60 also applicable to the conversion of 2,3-dim'ethyl butane
and 2,3-dimethyl butenes to 2,3-dimethyl butadiene.
A typical prior art dehydrogenation process as de
What is claimed is:
' ‘
scribed in this invention using calcium nickel phosphate
1. In a continuous process for dehydrogenating ole?ns
catalyst has been in operation since 1950. Because of
to diole?ns over a ?xed bed of dehydrogenation catalyst
the expensive nature of the catalyst, operation per charge
of catalyst must be at least 6 months to pay oil the catalyst 65 wherein C4 to C6 ole?n vapors are passed through the bed
during the dehydrogenation reaction cycle and wherein an
investment. Early runs (1951-1952) were not in excess
oxygen-containing gas is passed through said bed during
of 6 months and often as low as 2 month’s duration.
the regeneration cycle to reactivate the catalyst, the im
They were terminated by the formation of serious carbon
provement which comprises passing the vapors through a
mounds that were allowed to form to large size relatively
undetected.- It was found impossible to satisfactorily re 70 catalyst bed longitudinally divided into a plurality of sec
occurred.
_
-
generate these mounds so that the ‘catalyst had to be
discarded.
>
'
From 1953 on due to the greatly increased use of
detection devices such as thermocouples and ’round the
tions that are parallel to the ?ow of vapors through said
bed, determining the carbon dioxide content of the etlluent
gas in the several sections during regeneration and locat
ing catalyst deactivating carbon mounding in a section of
clock manning of the process by technical personnel to 75 the catalyst bed by the presence of higher than normal
3,092,674
5
carbon dioxide content in the ef?uent regeneration gas
from said section, blanking OK the section having carbon
mounding therein during the dehydrogenation cycle there
by preventing fnrther deactivation and opening said blank
ed-o? section ‘during the regeneration cycle thereby restor
ing the activity of the catalyst.
2. The process of claim 1 in which the ole?ns are
-
butenes.
3. In a continuous vapor phase process for dehydro
genating ole?ns to diole?ns over a ?xed bed of dehydro
genation catalyst wherein superheated steam and C4 to C6
ole?ns are passed through the bed during the dehydro
6
occurred, blanking off any section {of the catalyst bed
having carbon mounding therein during the dehydrogena
tion cycle and opening said blanked-o? section during the
regeneration cycle and repeating the procedure of blank
ing o? during dehydrogenation and ‘opening during re
generation until the carbon dioxide ‘analysis of the e?iuent
gas from said section during regeneration indicates that
catalyst activity has been restored ‘and thereupon resum
ing dehydrogenation in said section.
10
4. The process of claim 3 in which the C4 to C6 ole?ns
genation reaction cycle and wherein steam and excess
oxygen-containing gas are passed through said bed during
the regeneration cycle to reactivate the catalyst, the im 15
provement which comprises passing the olefms through a
catalyst bed longitudinally divided into ‘a plurality of uni
are butenes.
5. The process of claim 3 in Which the dehydrogenation
catalyst is ‘a calcium nickel phosphate catalyst.
References Cited in the ?le of this patent
UNITED STATES PATENTS
form sections that are parallel to the ?ow of ole?ns
2,423,835
through said bed, analyzing the carbon dioxide content of
the ei?uent ‘gas from‘ each section during the regeneration 20
cycle in order to locate ‘any sections of the catalyst
bed in which catalyst deactivating carbon mounding has
2,474,014
Houdry ______________ __ July 15, 1947
Seebold _____________ __ June 21, 1949
2,641,619
2,666,692
2,835,560
Noddings et al __________ __ June 9, 1953
Dolezal et a1 __________ __ Jan. 19, 1954
Bason et a1. __________ __ May 20, @1958